Shag
Phalacrocorax aristotelis (Linnaeus, 1761)
Order Pelecaniformes
Family Phalacrocoracidae
Conservation status: in Bulgaria: Vulnerable VU [D2], BDA-III; International: BD-I.
General distribution. A species with a North Atlantic type of distribution that embraces the Atlantic coast of Europe and Northwestern Africa and the coasts of the Mediterranean, the Adriatic Sea and the Black Sea.
Distribution and abundance in Bulgaria. Resident. It breeds along the rocky shore from cape Shabla to cape Kaliakra [1, 2], without any essential changes having been registered in the breeding area. In 1985, the numbers of the breeding population were about 25-30 [1]; in 1992 they were 50, in 1993 they were 62, in 1995 more than 80 pairs [3]; in 1997 the estimate was 10-50 pairs [4], and at present it is about 130-170 pairs [5], and even 180-250 pairs [6]. It is possible for the latter estimate to have been exaggerated. There is, however, a slow increase of the numbers and the population ought to be considered stable. In the winter, the species stays in the same area or goes down south, almost along the whole Bulgarian shore [2, 7]. The average numbers of wintering birds for the 1977-1996 period was 28 (3-74) individuals, with a maximum of 74 in 1990. Most of the individuals (75%) remain along the shore of Southern Dobrudzha [7]. Although the breeding population is considered to be residential, winter migrations have not been not well clarified. Outside the breeding period, large concentrations are observed at a considerable distance from the breeding sites [3].
Habitats. Vertical shore rocks with holes and caves, shore lakes, mouths of rivers, etc.
Biology. It breeds singularly or in small groups in shore caves and rock niches. Laying eggs starts probably at the beginning of April to the middle of the month. The clutch contains 3-6 white eggs. The breeding success is 0,34-0,4 young ones/pair [8]; it has been higher in recent years, ensuring the slow increase of the population. It feeds mainly on small fish (predominantly tadpoles) and crustaceans [2, 8].
Similar species. The Cormorant (Phalacrocorax carbo).
Negative factors. Disturbance as a result of the intensification of tourism and the increased presence of fancy fishermen, tourists, etc. It is not known what the quantity of accidentally caught birds in the local fishing nets is and to what extent it has an effect on the numbers of the population.
Conservation measures taken. Protected according to the Biological Diversity Act. Some of the breeding population is located on the territory of Kaliakra Reserve.
Conservation measures needed. More detailed studies on the population of of the species.
References. 1. Boev, 1985 2. Simeonov et al., 1990; 3. Nankinov, 2001; 4. Kostadinova, 1997; 5. Nankinov et al., 1994; 6. BirdLife International, 2004; 7. Michev & Profirov, 2003; 8. Nonev, 1978.
Authors: Bozhidar Ivanov, Nikolai Karaivanov, Dimitar Georgiev
